Vulcanization of rubber



Patented Nov. 25, 1930 j PATENT OFFICE-1 WHABRY counter], or new YORK, N. Y. 5

I VULCANIZATION OF RUBBER gamm Original application filed December 21, 1922, Serial No, 608,335. wa and thiaappiica- This invention relatesto the vulcanization of rubber; and it comprises a method of vul- -canizing rubber with sulfur wherein such vulcanization is performed in the presence 5 of a material resulting fromthe co-condensation of a cyanamid, an aldehyde and an amine; all as more fully hereinafter set forth and as claimed. 1 j

In the vulcanization of rubber with eles o mental sulfur or its equivalents; such as selenium, etc, by heating the rubber-sulfur mixture'above the melting point of sulfur, it has always been known that such metallic bases as zinc oxid, lead oxid, lime and magnesia bodies belonging to quite other classes: those resulting. from the co-condensation of a cyanamid, an aldehyde and an amine.

Calcium cyanamid or lime nitrogen occurs in commerce, being marketed mostly as a fertilizer, but is not particularly useful for the present purposes as it is onlysluggishly reactive, a fact which is probably due to the high temperature at which the commercial material is made. But many active accelerators containing the cyanamid group can be made with the aid of this commercial lime nitrogen as a raw material, by separating the lime in well known ways, such as treatment with water, weak acids, such as carbonic acid, or dilute sulfuric acid, etc.

It is well known that'cyanamid on standing or heating polymerizes to dicyandiamid and other polymerized compounds. The dicyandiamid'can readily be produced in crystallized form as a white permanent crystal preparation.

The cyanamid compounds may be advantageously joined with various of the ordihydrochloric or other acid to promote-mu ating agents.

nets are of av different naturebut they also nary organic accelerators, such as thiocar-' I tion filed May 29, 1926'. Serial No.:112,693.

banilid, toluidines, dimethylamine, piperidine, and anilin". The combination of orthotoluidine and dicyandiamid makesan especially valuable vulcanization acceleratorg In making this accelerator and others of its class, dicyandiamid is dissolved in a minimum quantity of water and the orthotoluidine,

or other amine such as anilin or dimethylamine, is added with the addition of enough tual solution while heated. Onlcooling, crystals separate out which,when dried and ground, are used as the accelerator. In my application Serial No. 608,355 whichma tured into Patent No. 1,593,017, I have at claimed processes of vulcanizing rubber in i which these compounds are used as acceler- I further disclosed inmy above mentioned application that the aldehyde condensation o products of the amines in the presence of a cyanamid compound are suitable for use as rubber accelerators; that is the reaction productsformed by condensing together aldehyde, cyanamid and an amine. ent application is a division of my said c opending application Serial No.608,355, filed 3 Dec. 21, 1922, which matured into Patent No,

1,593,017, and itrelates to processes of vulcanizing rubberfdisclosed but not claimed in the said copendin'g application," namely, processes of vulcanizing rubber inthe presence of the reaction products formed by condensing together aldehyde, cyanamid and amine, of which the above mentionedamines aretypical, I have found that if, instead ofmerely reacting together an amine and a cyanamid as claimed in my acknowledged prior application, there isadded a thirdreactant, namely, aldehyde, thereaction prodpossess the property of functioning-as rubber accelerators. The reactionproductsof aldehyde cyanamid amine condensation, whatever they may be, are all useful in proc5 esses of vulcanizing rubber. The'exact conditions of condensation may be varied over a wide range and various amines and aldehyde's may beused. But solong as'tho three specified reactants are condensed together The preshe products are useful in these rubber processes. The accelerating action of many of these compounds is quite marked. They are particularly valuable because they are either crystalline or resinous substances and for this reason they are more readily incorporated into the rubber mix.

As an example anilin, cyanamid and formaldehyde solutions may be mixed in aqueous, alcoholic or acid solution and the solid condensation products separated, purified and ground for use as an accelerator.

In vulcanizing rubber by the aid of the above accelerators, it is well to break down the raw rubber on heated rolls and if, for eX- ample, a tire tread is to be made about equal quantities of rubber and pigments, such as zinc oxid, gas black, etc, are mixed with sulfur, the amount of sulfur being from 4 to 6 per cent of the rubber. The pigments are incorporated in the rubber by continuous mixing on the rolls which may be quite warm without danger of scorching. When the pigments and other materials are thoroughly incorporated, the mass is taken from the rolls and used as a mother batch when it has cooled or preferably stood for several days. Then to 100 parts of mother batch, which is re-plasticized on cooler rolls, 1 part of the above accelerators is added; and if vulcanized at 45 pounds steam pressure for 1 hour, agood product is obtained. The quantity of the accelerator may vary according to the hardness of cure desired, the slowness of normal vulcanization of rubber compound under treatment, the heat used and other factors known to the expert.

The aldehyde-amine-cyanamid condensation products above described and claimed in the appended claims have advantageous uses in the vulcanization of rubber under conditions where it is desirable to incorporate the accelerator in the form of a solid or semi-solid material in the rubber mix.

This application is a division of an application of Harry 0. Chute, Serial No. 608,355, filed December 21, 1922, which matured into Patent No. 1,593,017 on July 20, 1926.

What I claim is 1. In the vulcanization of rubber the process which comprises vulcanizing such rubber in the presence of the reaction product of a cyanamid, formaldehyde and an amine.

2. In the vulcanization of rubber the process which comprises vulcanizing such rub ber in the presence of the reaction product of anilin, cyanamid and formaldehyde.

3. In the vulcanization of rubber the process which comprises vulcanizing such rubber in the presence of the reaction product of a cyanamid, formaldehyde and a primary amine.

4. In the vulcanization of rubber the process which comprises vulcanizing such rubber in the presence of the reaction product of a cyanamid product, formaldehyde and a primary aryl amine.

5. In the vulcanization of rubber the process which comprises vulcanizing such rubber in the presence of the reaction product of a cyanamid product, formaldehyde and a primary monocyclic aryl amine.

6. In the vulcanization of rubber the process which comprises vulcanizing such rubber in the presence of the reaction product of a cyanamid, a formaldehyde and a primary amine.

7. In the vulcanization of rubber the process which comprises vulcanizing such rubber in the presence of the reaction product of acyanamid, a formaldehyde and a primary aryl amine. I

8. In the vulcanization of rubber the process which comprises vulcanizing such rubber in the presence of the reaction product of a cyanamid, a formaldehyde and a primary monocyclic aryl amine.

9. In the vulcanization of rubber the process which comprises vulcanizing such rubber in the presence of the reaction product of a cyanamid, formaldehyde and an amine selected from a group consisting of thiocarbanilid, toluidine, dimethylamine, piperidine and aniline.

1 0. In the vulcanization of rubber the process which comprises vulcanizing such rubber in the presence of the reaction product of a cyanamid, formaldehyde and a phenyl amine.

11. In the vulcanization of rubber the process which comprises vulcanizing such rubber in the presence of the reaction product of a cyanamid, formaldehyde and a phenyl amine selected from a group consisting of thiocarbanilid, toluidine and aniline.

In testimony whereof, I have hereunto affixed my signature.

HARRY O. CI-IUTE. 

